Design of hemocompatible poly(DMAEMA- co -PEGMA) hydrogels for controlled release of insulin

How does the polymer architecture and position of cationic charges affect cell viability?

Polymer chemistry, composition and molar mass are factors that are known to affect cytotoxicity, however the influence of polymer architecture has not been investigated systematically. In this study the influence of the position of the cationic charges along the polymer chain on cytotoxicity was investigated while keeping constant the other polymer characteristics. Specifically, copolymers of various architectures, based on a cationic pH responsive monomer, 2-(dimethylamino)ethyl methacrylate (DMAEMA) and a non-ionic hydrophilic monomer, oligo(ethylene glycol)methyl ether methacrylate (OEGMA) were engineered and their toxicity towards a panel of cell lines investigated. Of the seven different polymer architectures examined, the block-like structures were less cytotoxic than statistical or gradient/tapered architectures. These findings will assist in developing future vectors for nucleic acid delivery.

Polyaspartic acid, 2-acrylamido-2-Methyl propane sulfonic acid and sodium alginate based biocompatible stimuli responsive polymer gel for controlled release of GHK-Cu peptide for wound healing

Stimuli responsive polymer based on Polyaspartic acid, 2-Acrylamido-2-methylpropane sulfonic acid and sodium alginate (NaAlg) were synthesized using two cross-linkers Ethylene glycol dimethacrylate (EGDMA) and TMPTA (Trimethylolpropane triacrylate). The polymers were standardized and optimized to obtain a polymer with maximum swelling in distilled water, saline, glucose and solutions of varying pH. The synthesized polymer swelled well in distilled water, glucose solution and acidic- alkaline medium. The biocompatibility of the polymer was evaluated for blood compatibility and protein adsorption. The polymer with maximum swelling property was used for peptide release studies. The polymer was further used to study the peptide encapsulation and release efficiency of the polymeric material which was confirmed by FTIR, Scanning Emission Microscope and EDX. The encapsulation efficiency of the polymer for encapsulating (glycyl-l-histidyl-l-lysine-copper) GHK-Cu was observed to be 55.26% and peptide release of 51.84% was observed for Ethylene glycol dimethacrylate based polymer after 24 h whereas for Trimethylolpropane triacrylate based polymer the encapsulation efficiency was observed to be 49.6% and release was 39.01%. The EGDMA based polymer was further examined under in vivo studies in order to evaluate the efficiency of the synthesized polymer. The in vivo studies include wound closure, histopathological analysis, biochemical and toxicity assay. The material has shown promising results for both in vivo and in vitro studies.

Acceleration of Wound Healing in Diabetic Rats through Poly Dimethylaminoethyl Acrylate-Hyaluronic Acid Polymeric Hydrogel Impregnated with a Didymocarpus pedicellatus Plant Extract

Wound is the major health problem associated with skin damages and arises because of various types of topical injuries. Furthermore, wounds in patients with diabetes take a relatively long time to heal. Currently, herbal medicines have been extensively used for wound care and management. Here, we engineered polymeric hybrid hydrogel of dimethylaminoethyl acrylate and hyaluronic acid (pDMAEMA-HA), which was impregnated with a herbal extract of Didymocarpus pedicellatus. The developed polymeric hybrid hydrogel system can be used for effective therapy of incurable wounds. Therefore, the development of D. pedicellatus-impregnated pDMAEMA-HA (pDPi-DMAEMA-HA) hybrid hydrogel was accomplished by the synthesis of pDMAEMA-HA hydrogel via the optimization of various reaction parameters followed by impregnation of herbal drugs D. pedicellatus. The developed hydrogel composite was well characterized via various techniques, and swelling kinetics was performed to analyze the water uptake property. The swelling ratio was found to be 1600% in both types of hydrogels. To evaluate the wound healing of these polymeric hydrogels, the Wistar rats full-thickness excision wound model was utilized. The healing strength of hydrogels was determined using measurement of wound contraction and histopathological study. The results of wound healing by these polymeric hydrogels revealed that animals treated with the pDPi-DMAEMA-HA hybrid hydrogel group were found to have a higher level of wound closure as compared to marketed formulation as well as polymeric hybrid hydrogel. The histopathologic examinations implied that pDPi-DMAEMA-HA hybrid hydrogel and polymeric hybrid hydrogel-treated groups exhibited enhanced cutaneous wound repair as well as high level of cellular repair and maintenance compared to the standard group because of hyaluronic acid roles in various stages of wound repair.

In Vitro and in Vivo Studies of pH-Sensitive GHK-Cu-Incorporated Polyaspartic and Polyacrylic Acid Superabsorbent Polymer

The main aim of this study was to evaluate the in vitro and in vivo efficiency of the polyaspartic acid- and acrylic acid-based superabsorbent polymer. The synthesized polymer was first investigated to check the blood compatibility by protein adsorption and blood clotting tests. Further, the GHK-Cu peptide was incorporated within the polymer and release studies were performed to evaluate the drug-delivery efficiency of the superabsorbent polymer. The polymer with best peptide release results were further used for in vivo analysis for wound healing. The healing efficiency of polymer with and without peptide was analyzed using wound closure, biochemical assay, histopathological, and toxicity studies.

A facile method to fabricate thermo- and pH-sensitive hydrogels with good mechanical performance based on poly(ethylene glycol) methyl ether methacrylate and acrylic acid as a potential drug carriers

A thermo- and pH-sensitive hydrogel was prepared by a facile free aqueous radical copolymerization of PEGMA and AAc without any crosslinkers for controlled drug delivery. The successful fabrication of hydrogels was confirmed by Fourier transform infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TGA) measurements. The morphological, mechanical and swelling properties of the obtained hydrogels were studied systematically. The results showed that the morphological and mechanical behaviors of the resultant hydrogels were strongly affected by the content of AAc. Moreover, the obtained hydrogels showed an excellent thermo-, pH- and salinity sensitivities. Release profiles of 5-Fu were studied at different pH (gastric pH 1.2 and intestinal pH 7.4) and temperatures (25 °C and 37 °C). The results showed that the release is very low at pH 1.2/37 °C and high at pH 7.4/25 °C. The cytotoxicity of hydrogels to cells was determined by an MTT assay. The result demonstrated that the blank hydrogels had negligible toxicity to cells, whereas the 5-Fu-loaded hydrogels remained high in cytotoxicity for LO2 and HepG-2 cells. Results of the present investigation exemplify the potential of this novel thermo- and pH-sensitive hydrogel for the controlled and targeted delivery of the anti cancer drug 5-Fu.

Stimuli-responsive nanocarriers for intracellular delivery

The emergence of different nanoparticles (NPs) has made a significant revolution in the field of medicine. Different NPs in the form of metallic NPs, dendrimers, polymeric NPs, carbon quantum dots and liposomes have been functionalized and used as platforms for intracellular delivery of biomolecules, drugs, imaging agents and nucleic acids. These NPs are designed to improve the pharmacokinetic properties of the drug, improve their bioavailability and successfully surpass physiological or pathological obstacles in the biological system so that therapeutic efficacy is achieved. In this review I present some of the current approaches used in intracellular delivery systems, with a focus on various stimuli-responsive nanocarriers, including cell-penetrating peptides, to highlight their various biomedical applications.